1. Field of the Invention
Embodiments of the present invention generally relate to a method for processing magnetic film stacks. More specifically, the invention relates to a method of preventing an electrical short circuit while fabricating magneto-resistive random access memory (MRAM) devices.
2. Description of the Related Art
Microelectronic devices are generally fabricated on a semiconductor substrate as integrated circuits wherein various layers of materials must be deposited and patterned to form the device. An example of such a device is a magneto-resistive random access memory (MRAM) device.
An MRAM typically comprises a multi-layer film or “film stack” that may be processed to form an information storage element. The film stack comprises magnetic materials that are typically etched at high temperature using, for example, a plasma etch process. The plasma may comprise, for example, fluorine or chlorine species. The chlorine or fluorine species may combine with material removed from material layers in the film stack to form a conductive residue that deposits along the sidewalls of the film stack.
The conductive residue may form in various manners. For example, if a layer in the film stack comprises tantalum, a plasma etch process utilizing chlorine (Cl2) may result in the formation of tantalum chloride (TaCl) residue. If a photoresist layer comprising carbon is used to pattern the film stack during the etch process, a metal-containing polymer may also form as an additional residue resulting from the etch process. Alternatively, the residue may result from a by-product of the plasma etchant reacting with the removed material. Generally, the conductive residue that deposits on the sidewalls of the film stack is tenacious and difficult to remove. The conductive residue may form a conductive pathway that acts as an electrical short circuit across layers of the MRAM device, thereby rendering the device inoperable.
Therefore, there is a need in the art for a method of preventing electrical short circuiting in magnetic film stacks such as the film stacks used in magneto-resistive random access memory (MRAM) devices.